Two-stroke cycle internal-combustion engine of the diesel type



May 18, 1926.

F'. SCHMALJOHANN TWO-STROKE CYCLE INTERNAL COMBUSTION ENGINE OF THE DIESEL TYPE Filed April l5. 1924 17 f PAM/L SCH/17H1. JO//a/V/V LPatented yMay' 18, 1'926.

PATENT OFFICE.

PAUL SCHMALJOHANN, OF KIEL, GERMANY.

TWO-STROKE CYCLE INTERNAL-COMBUSTION ENGINE F THE DIESEL TYPE.

Application filed April 15.` 1924, Serial No. 706,657.

My invention relates t`o improvements in two-stroke cycle internal combustion engines of the Diesel type, and more particularly in engines of the type comprising stationary cyl- 6 inders and reciprocating pistons acting on a, rotary member or fly wheel mounted on the driven shaft and formed With cam ways controlling the cycle performed in the cylinders. l In order to reduce the size and the 10 Weight of engines of this type the cam ways are so constructed that for each rotation of the fly wheela plurality of cycles are performed in each of the cylinders. However, thereby the time for the individual cycles is unduly shortened. This is not objectionable as far as compression and expansion are concerned, but the regular combustion of the fuel requires a certain time and it must be completed as far as possible at the beginning of the expansion, because otherwise the efficiency of the engine is interfered with by retarded combustion. .The object of the improvements is to provide an engine of the class referred to in which .a plurality of cycles are performed. for each rotation of the fly Wheel, and in which the time allowed for the combustion is suliicient to insure complete combustion, and with this object in view my invention consists in constructing the portions of the cam ways corresponding to the combustion strokes so that the length of the portions results in an increased time of combustion, and that during this period of time the pistons move through paths corresponding in the diagram to the line of equal pressure. In my improved engine it can not be entirely avoided that the combustion of a part of the fuel is delayed and that the delayed combustion is continued in u large part of the expansion portion of the cycle if the period of time of the expansion is short. For this reason the cam ways are made so that the expansion period also is lengthened, while the time of 5 the compression is reduced, which reduction.

however, is'immaterial. By thus constructing the cam ways the time of the complete two-stroke cycle remains the same, and by extending the period of time of the eX- pansion the delayed combustion takes place durin a short part of the said expansion perio so that the loss caused by delayed combustion is reduced to a minimum.

For the purpose of explaining the invention an example embodying the same has been shown in the accompanying drawing, in which,

.Fig 1, is a sectionalelevation of the engine, and

Figs. 2 and 3, are diagrammatical views showing the form of the cam way,

In the e'iiample shown in the drawing the Itwo-stroke cycle. The cam Way is formed on the inner face of a tly wheel or disk 8 secured to the driven shaft.

Thel piston 2 controls the exhaust ports 9 and the piston- 3 the ports 1()l for the admission of scavenging air. The fuel is `fed through apertures 11 of the cylinden l. During the explosion stroke the pistons 2 and 3 and the rollers 7 thereof are forced against the portions c-) of the cam ways, so that the i'ly wheel 8 is driven in the direction indicated by the arrow m shown in Fig, 1.

In Fig. 2 I have shown a section b--b of the guide Way corresponding to a complete two-stroke cycle, as Vdeveloped on a straight line, together With the indicator diagram drawn in the proper lrelation thereto. The section b-c corresponds tothe compression line f--g of the indicator diagram, the section c-d to the line g-h of constant pressure combustion, and the line d-b to the line h-f of the expansion.

The lengths b-c and c-Z when measured by arcs are represented by the lengths Z and m respectively which are alike, and which correspond to certain periods of time.

The dotted line c-eb shows the form of the cam way of engines with normal crank mechanism as constructed hitherto, the curve c-'e-b being exactly-symmetrical to b-a In engines of this type the line of equal pressure represented in the diagram by the linel g--t corresponding to a definite piston stroke is passed by the iston within a period of time corresponding to the length 2'.. But when the ide Way is shaped according to my present mvention, as indicated, by the line c-af-b the piston passes through the same vlength g-h of its stroke during a longer period of time corresponding to the line It, so that there is sufficient time for the combustion even in case of a high number of revolutions of the engine. In my present invention, the section c-d-b is unsymmetrical with respect to the section 6 0.

In the diagram shown in F ig. 3 the point c has been shifted to the left for shortening the length fn relatively to what has been shown in Fig. 2, and the length o has been increased accordingly as Compared With m. rIhe'length has not been changed, so that the expansion is extended in a degree corresponding to the difference of the lengths la and o. Therefore, delayed combustion takes place only on a comparatively small part of the expansion stroke cZ-b.

I claim:

l. In a two-stroke cycle internal combustion engine, the combination, with a cylinder, and a piston, of a cam Way engaged by said piston for controlling the movement thereof, that, portion of thecurve of the cam Way which controls the combustion and expansion being unsymmetrical with respect to the remaining portion of the cam curve in such a way as to increase the time of the combustion Without, changing the length of the stroke of the piston.

2. In a two-stroke cycle internal combustion engine, the combination, with a cylinder, and a piston, of a cam way engaged by said piston for controlling the movement thereof, that port-ion of the curve of the cam way which controls the combustion and compression being unsymmetrical with respect to the remaining portion of the cam curve in such a Way as to accelerate the, movement of the piston during the compression stroke and to begin the combustion stroke accord- 3. In a two-stroke cycle internal combustion engine, the combination, with a cylinder,

and a piston, of a cam Way engaged by said piston for controlling the movement thereof, that portion of the curve of the cam Way Which controls the combustion, expansion and compression being modified from the curve corresponding to the operation by means of a crank mechanism in such a Way as to accelerate the movement of the piston during the compression stroke and begin the combustion stroke accordingly and retard the movement of the piston during the combustion and expansion stroke.

4:. In a two-stroke cycle internal combustion engine, the combination, with a stationary" cylinder, and a piston reciprocating therein, of a rotary annular driven member formed with a cam Way engaged by said piston for controlling the movement thereof and for being driven thereby, that portion of the curve of the cani Way which controls the combustion and expansion being modified from the curve corresponding to the operation by means of a c.' ank mechanism in such a Way as to increase the time of the combustion without changing the length of the stroke of the piston.

In a two-stroke cycle internal combus- `tion engine, the combination, with a stationary cylinder, and a piston reciprocating therein, of a rotary annular driven member formed with a cam way engaged by said piston for controlling the movement thereof and for being driven thereby, that portion of the curve of the cam way which controls the con'ibnstion and compression being modilied from the curve corresponding to the operation by means of a crank mechanism in such a way as to accelerate the movement of the piston during the compression stroke and begin the combustion stroke accordingly.

In testimony whereof I hereunto alix my signature.

PAUL SCHMALJOHANN. 

